The first official visit to China by a Vietnamese premier in six years, Phuc’s trip came at the invitation of Chinese counterpart Li Keqiang. Vietnamese and Chinese media are reporting that Phuc and Li jointly pledged to "manage maritime differences" and "maintain peace and stability" at a Monday news conference that followed wide-ranging talks at the Great Hall of the People.

Phuc's visit coincides with the launch of annual Sino-Russian naval drills, which, according to Chinese military officials, will include simulated "seizure and control" of contested islands and shoals. Foreign Ministry spokesperson Hua Chunying said the training exercises aren't "against any third party.”

State Department spokesman John Kirby addressed the Chinese-Russian wargames Monday, saying the U.S. doesn't perceive them as a threat.

"The only thing we are mindful of is that the exercise should be in accordance with international law, not raising tensions," he said.

Duong Danh Dy, a former senior Vietnamese diplomat who once worked as general consul in Guangzhou, says the invite extended to Phuc “clearly shows that China wants to ease tensions.”

“Vietnam’s capacity is growing, so it cannot be ignored in the disputes over the South China Sea,” he said, adding that Vietnam “is not an important factor” in Beijing-Moscow relations.

Trust-building

Some view Phuc's visit as part of Vietnam's trust-building efforts with its northern neighbor — the most populous country in the world — part of a comprehensive diplomatic campaign to gather support from the international community.

In a keynote speech during his visit to Singapore last month, Vietnamese President Tran Dai Quang warned that any countries that engage in armed conflict over the resource rich waterway will be destined to lose more than they would gain from combat. He did not mention any country by name.

Meanwhile, Nguyen Xuan Cuong, head of the Institute of Chinese Studies, says the two nations are facing both opportunities and challenges.

“The two sides still have differences over the South China Sea issue," he said. "The visit is a chance for them to find solutions and strengthen mutual trust.”

But Dy, the former diplomat, says it may be a long time before the two nations find common ground amid conflicting claims of maritime sovereignty.

“Building trust will never happen," he said. "They only make [an] effort to prevent wars from breaking out. That’s it.”

The news portal of the Vietnamese government quoted Phuc as saying that he would engage with Chinese officials on exchanging measures to stabilize relations between the two countries.

During talks, both premiers witnessed the signing of agreements on trade, production capacity, infrastructure, education and tourism.

Phuc is on his first official visit to China since assuming office in April.